[RE-wrenches] Troubleshooting Stumper - Homerun Interference in Conduit/Inverter Turning Off/On Rapidly

jay jay.peltz at gmail.com
Wed Sep 7 17:58:28 PDT 2016


hate to ask the obvious here, but you mean to say that volts and polarity are correct on both sets of wires at the inverter when not connected?

and

2. what wattage modules are you using?

jay
peltz power








> On Sep 7, 2016, at 2:45 PM, Matt Partymiller <matt at solar-energy-solutions.com> wrote:
> 
> Wrenches,
> 
> One of our systems is having an issue I have not encountered before where
> the inverter switches between nighttime mode and interconnection every few
> seconds.  I am hoping for some technical wisdom from the community.
> 
> We have an array of 20 TrinaSmart modules in two strings of 10.  The array
> is connected to a Solectria 3.8 kW inverter.  The conduit run is simple,
> all four homerun wires (#10 PVwire) in 1" EMT down to the proximity of the
> Solectria inverter where the conduit switches to 1" LFMC before entering
> the inverter.  The run is about 20', straight down the side of the wall
> before hitting the inverter.  A 600V jacketed communications wire was also
> in the conduit but has since been removed and run separately.
> 
> Our inverter is starting up, running for a few seconds, giving a low
> voltage error, briefly showing nighttime mode, then going into startup
> mode again.  Solectria was gracious enough to send us a new inverter but
> we have the exact same issue.  They tell us their error codes (266, 274)
> indicate 0 volts.  The transition between low voltage error and startup is
> almost instant.  Basically we have 20 seconds of start up, 5 seconds of
> run, 5 seconds of error then repeat.  This is not a grid problem, the
> identical system next door works fine.
> 
> In the process of troubleshooting, our technician pulled all four homerun
> wires out of our conduit and meggered them.  They all tested fine so he
> connected to the inverter.  The inverter worked fine.  The technician
> verified grounding of the array and conduit, pulled new homeruns back
> through the conduit, and reconnected to the inverter.  He had the same
> error as before.
> 
> He connected each string separately to the inverter by removing the string
> fuses.  Either string will operate fine independently.  With string one in
> conduit and either homerun of string two in conduit (but not both) the
> inverter operates fine.  With string two in conduit but string one outside
> of conduit, the inverter does not operate.
> 
> I was certain the error had something to do with homerun roof wiring so I
> went out with the technician and removed and checked pretty much every
> module.  Everything appears fine, all connections solid, all homeruns have
> been remade at least once at this point.  Now I am stumped and lack the
> technical knowledge to diagnose the problem.  I would be extremely
> grateful if an esteemed wrench can provide technical support/advice.
> 
> Thanks,
> 
> Matt
> 
> 
> 
> 
> Matthew Partymiller
> Solar Energy Solutions LLC
> (877) 312-7456
> matt at solar-energy-solutions.com
> 
> 
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